Exhaust trap device

ABSTRACT

Three exhaust trap units are arranged in series in an exhaust trap device for trapping substances solidified from exhaust gas and exhaust gas paths are formed inside the exhaust trap units. One or more collision plates are placed in each trap unit. The collision plates in each of the two upstream side exhaust trap units are arranged such that a space extending in the axial direction of the exhaust path is present therein without being blocked by any of the collision plates. The collision plates in the downstream side exhaust trap unit are arranged such that such a space is not present. Uneven distribution of the amount of accumulation of solidified substances is suppressed without performing complex control, and outflow of the solidified components to the downstream side of the exhaust trap device can be reliably reduced.

FIELD OF THE INVENTION

The present invention relates to an exhaust trap device; and, moreparticularly, to the structure of an exhaust trap device that exhibitsenhanced trapping efficiency to thereby reduce outflow of solidifiedcomponents toward a downstream side of the exhaust trap device.

BACKGROUND OF THE INVENTION

In general, various gas reaction apparatuses for forming films on asubstrate or etching the substrate have been used as semiconductormanufacturing apparatuses. Typically, such a gas reaction apparatusesincludes a gas supply unit, a hermetic gas reaction chamber suppliedwith a gas from the gas supply unit, an exhaust route connected to thegas reaction chamber and an evacuation device, such as a vacuum pump orthe like, connected to the exhaust route.

Such gas reaction apparatuses suffer from a problem that reactionby-products are solidified from the exhaust gas discharged out of thegas reaction chamber and are accumulated in the exhaust route or theevacuation device, which may lead to clogging of the exhaust route orfailure of the evacuation device. Taking this into account, an exhausttrap device is arranged midway of the exhaust route to perform the taskof trapping the reaction by-products present in the exhaust gas (seeJP8-13169A, JP8-24503A and JP8-299784A, for example). Most frequentlyused as such kind of exhaust trap device is a collision-type cooling andtrapping device in which collision plates, such as baffle plates, finsor the like, are arranged within a casing in an intersectingrelationship with respect to a flow direction of the exhaust gas. Thedevice is constructed such that, as the exhaust gas collides against thecollision plates and is subjected to cooling, given kinds of solidifiedsubstances can be accumulated on the surface of the collision plates. Inthis collision-type cooling and trapping device, the shape andarrangement of the collision plates is optimized so as to increasetrapping efficiency, thereby reducing outflow of the solidifiedsubstances toward a downstream side of the device.

Also proposed are exhaust trap devices each having a plurality ofexhaust trap sections arranged in series along an exhaust route (seeJP10-73078A, JP2000-256856A, JP2001-131748A and JP2001-329367A, forexample). Examples of such exhaust trap devices include a device that,by employing a plurality of serially arranged exhaust trap sectionswhose cooling temperatures differ from one another, can increasetrapping efficiency or can allow the respective exhaust trap sections totrap different kinds of solidified substances (JP10-73078A,JP2000-256856A and JP2001-329367A) and a device that can improvemaintainability by distributing the accumulation of solidifiedsubstances over a plurality of exhaust trap sections (JP2001-131748A).

In the collision-type cooling and trapping device referred to above, theexhaust gas introduced into the device through a gas inlet port makescontact with the collision plates within an exhaust path and is rapidlycooled down. For this reason, the reaction by-products are adhered toaround the gas inlet port in large quantities and the exhaust path showsa reduced conductance. This makes it impossible to keep the gas reactionchamber arranged at the upstream side in a vacuum condition or causesclogging in the vicinity of entrance of the exhaust path, which in turnposes a problem that the exhaust trap device needs to be maintained atan increased frequency.

To avoid such a problem, there is a need to raise the coolingtemperature in the exhaust path. However, if the temperature in theexhaust path is raised, the reaction by-products cannot be sufficientlytrapped in the exhaust trap device and the reaction by-products aresolidified in an evacuation device or a scrubber arranged at thedownstream side of the exhaust trap device, which causes a shortenedmaintenance cycle or a failure of the evacuation device or a scrubber.

The trap device disclosed in JP2001-131748A includes a plurality of trapmembers arranged in multiple stages along a flow direction of theexhaust gas and also divided into multi-groups; heating units forindependently heating the respective groups of trap members, exceptingfor the group of trap members positioned downstreammost in the flowdirection of the exhaust gas; and a heat quantity controller forcontrolling the amount of heat generated by each heating units. Thisensures that the reaction by-products are accumulated first on thedownstreammost trap member and then on the upstream side trap members insequence, thereby avoiding uneven distribution in the amount ofaccumulation of the solidified substances on the plurality of trapmembers. With this trap device, however, the heating units are requiredto be controlled in a time-dependent manner, which makes a control unitcomplicated, and further the control needs to be performed in a highlysophisticated fashion depending on the constituents of the exhaust gas.In addition, since above-noted structure is primarily focused on theavoidance of uneven distribution in the amount of solidified substancesaccumulated within the trap device, the device suffers from a drawbackin that it is difficult to reduce the amount of reaction by-productssolidified at a more downstream side than the downstreammost trapmember.

SUMMARY OF THE INVENTION

In view of the foregoing problems, it is an object of the presentinvention to provide an exhaust trap device capable of suppressinguneven distribution in the amount of accumulation of solidifiedsubstances such as reaction by-products or the like without having toperform complicated control and reliably reduce outflow of thesolidified substances toward a downstream side.

In accordance with the present invention, there is provided an exhausttrap device for trapping solidified substances from an exhaust gaspassing through a gas exhaust route, including: a plurality of exhausttrap sections arranged in series along the exhaust route and havinginternally formed exhaust paths through which the exhaust gas passes,wherein the plurality of exhaust trap sections includes a first exhausttrap section arranged at an upstream side in a flow direction of theexhaust gas and a second exhaust trap section arranged at a downstreamside in the flow direction of the exhaust gas, wherein the first exhausttrap section is provided with a multiple number of collision platesarranged to interrupt an exhaust gas flow moving along an axis of anexhaust path of the first exhaust trap section, the multiple number ofcollision plates being arranged such that a space extending continuouslyalong the axis of the exhaust path without being interrupted by any ofthe collision plates arranged within the exhaust path exists in theexhaust path, and wherein the second exhaust trap section is providedwith a plural number of collision plates arranged to interrupt anexhaust gas flow moving along an axis of an exhaust path of the secondexhaust trap section, the plural number of collision plates beingarranged such that a space extending continuously along the axis of theexhaust path without being interrupted by any of the collision platesarranged within the exhaust path does not exist in the exhaust path.

In accordance with the present invention, in the exhaust trap sectionprovided at the upstream side, the specific arrangement pattern of thecollision plates ensures that a part of the exhaust gas passes throughthe exhaust path without colliding against the collision plates. Thisreduces the amount of accumulation of solidified substances and helpsavoid reduction in the conductance of the exhaust path and clogging ofthe exhaust path. On the other hand, in the exhaust trap sectionprovided at the downstream side, the specific arrangement pattern of thecollision plates makes sure that the entire exhaust gas is affected bythe collision plates. Thus, the collision plates can promote creation ofsolidified substances from the exhaust gas and accumulation thereof,thereby reducing outflow of the solidified components toward thedownstream side of the device. Accordingly, the amount of accumulationof the solidified substances are decreased in the upstream side exhausttrap section but increased in the downstream side exhaust trap section.This helps suppress uneven distribution in the amount of accumulation ofthe solidified substances between the exhaust trap sections, eventuallyreducing the frequency of maintenance. Further, even the unevendistribution in the amount of accumulation of the solidified substancesis suppressed, the configuration of the collision plates in thedownstream side exhaust trap section enables the reduction of theoutflow of the solidified components toward the downstream side of thedevice. This makes it possible to prevent failure of an evacuationdevice or a scrubber arranged at the downstream side of the device, thusrelieving the maintenance demand for these devices.

It is preferable that the plurality of exhaust trap sections areconstructed to be coupled to and separated from one another. This makesit possible to change the number of the exhaust trap sections or toreplace the exhaust trap sections with the ones having the collisionplates of different shapes or arrangement patterns, depending on thecircumstances, e.g., the components or temperature of the exhaust gas.As a consequence, the accumulation of solidified substances can beadjusted to thereby optimize the system for the reduction of themaintenance frequency and the outflow of the solidified components.

In accordance with the invention, an exhaust trap device for trappingsolidified substances from an exhaust gas passing through a gas exhaustroute, including: a plurality of exhaust trap sections arranged inseries along the exhaust route, each section having an internally formedexhaust path through which the exhaust gas passes, wherein the pluralityof exhaust trap sections includes a first exhaust trap section arrangedat an upstream side in a flow direction of the exhaust gas and a secondexhaust trap section arranged at a downstream side in the flow directionof the exhaust gas, wherein each of the first and the second exhausttrap section is provided with collision plates, and wherein angles thatan axis of an exhaust path makes with respect to the collision plates inthe second exhaust trap section are greater than angles that an axis ofan exhaust path makes with respect to the collision plates in the firstexhaust trap section.

In accordance with the present invention, the inclination angles thatthe collision plates make with respect to the axis of the exhaust pathin the upstream side exhaust trap section are small. Therefore, thecollision plates serve as rectifying plates that rectify the exhaust gasflow without interrupting same, while presence of the collision platesincreases the surface area of the exhaust path in contact with theexhaust gas, assuring the action of accumulation of solidifiedsubstances. Use of the rectifying plates makes it possible to ameliorateuneven distribution of the solidified substances within the exhaust pathand also to control the amount of accumulation of the solidifiedsubstances, thus avoiding reduction in the conductance of the exhaustpath or clogging of the exhaust path. On the other hand, the inclinationangles that the collision plates make with respect to the axis of theexhaust path in the downstream side exhaust trap section are large. Forthis reason, the exhaust gas flow is interrupted by the collisionplates, which allows the solidified substances to be accumulatedefficiently. Accordingly, the amount of accumulation of the solidifiedsubstances is decreased in the upstream side exhaust trap section butincreased in the downstream side exhaust trap part. This helps suppressuneven distribution in the amount of accumulation of the solidifiedsubstances between the exhaust trap sections, eventually reducing thefrequency of maintenance. Further, even the uneven distribution in theamount of accumulation of the solidified substances is suppressed, thecollision plates in the downstream side exhaust trap section are stillable to reduce outflow of the solidified components toward thedownstream side of the device. This makes it possible to prevent failureof an evacuation device or a scrubber arranged at the downstream side ofthe device, thus relieving the maintenance demand for these devices. Thecollision plates of the upstream side exhaust trap section may bearranged in parallel to the axis of the corresponding exhaust path.

In this case, it is preferable that the first and the second exhausttrap section are arranged such that one section is disposed outside theother section to surround same and a path inverting portion forinverting the flow direction of the exhaust gas is provided between thefirst exhaust trap section and the second exhaust trap section. Thisensures that the two exhaust trap sections of the upstream and thedownstream side can be configured compact and also integrated with eachother.

In this case, it is also preferable that the path inverting portion isconnected with the entire perimeters of the first exhaust trap sectionand the second exhaust trap section. With this configuration, the pathinverting portion allows the exhaust gas to flow from the upstream sideexhaust trap section toward the downstream side exhaust trap sectionover their entire perimeters, thus making it possible to increase thecross sectional passage area of the path inverting portion. This alsoreduces unbalance of the exhaust gas flow at the downstream portion ofthe upstream side exhaust trap section and at the upstream portion ofthe downstream side exhaust trap section, thereby avoiding reduction inthe conductance of the respective sections or clogging of the exhaustpaths.

In each of the inventions, it is preferable that the collision platesare arranged to allow the exhaust gas to spirally flow within theexhaust path in which the collision plates are arranged. This cancreates a vortex flow of the exhaust gas within the exhaust path, thuspromoting accumulation of the solidified substances and reducing theoutflow of the solidified components toward the downstream side of thedevice. In this case, the vortex flow may be created by a plurality ofspirally arranged collision plates or by a single spiral collisionplate.

In accordance with the present invention, there is further provided agas reaction apparatus including: a gas supply unit; a gas reactionchamber in which gases supplied from the gas supply unit are reacted; anexhaust route associated with the gas supply unit or the gas reactionchamber; and one of the exhaust trap devices described above, the one ofthe exhaust trap devices being arranged on the exhaust route. Examplesof the gas reaction apparatus include a gas film forming apparatus forforming a film on a substrate placed within a gas reaction chamber and agas etching apparatus for etching a surface of a substrate. Inparticular, it is preferable that the gas reaction apparatus is appliedto a variety of semiconductor manufacturing apparatuses employed in asemiconductor manufacturing process.

In accordance with the present invention, it is possible to attain anexcellent effect in realizing an exhaust trap device that can suppressuneven distribution in the amount of accumulation of solidifiedsubstances of reaction by-products or the like without performing anycomplicated control and can reliably reduce the outflow of thesolidified components toward a downstream side of the device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view showing the overall configuration of an exhausttrap device in accordance with an embodiment of the present invention.

FIG. 2 is a vertical cross sectional view depicting a first trap unit ofthe exhaust trap device shown in FIG. 1.

FIG. 3 is a partial cross sectional view illustrating fins arranged onan inner tube of the first trap unit of the exhaust trap device shown inFIG. 1.

FIG. 4 is a horizontal cross sectional view showing the first trap unitof the exhaust trap device shown in FIG. 1.

FIGS. 5A and 5B are vertical and horizontal cross sectional views of asecond trap unit of the exhaust trap device shown in FIG. 1.

FIGS. 6A and 6B are vertical and horizontal cross sectional views of athird trap unit of the exhaust trap device shown in FIG. 1.

FIG. 7 is a piping diagram illustrating the overall configuration of agas reaction apparatus in accordance with the present invention.

DESCRIPTION OF REFERENCE CHARACTERS

100 Exhaust trap device 110 First trap unit 120 Second trap unit 130Third trap unit 11X, 11Z, 12X, 13X Exhaust path 11Y Path invertingportion 113 Outer tube 114a, 114b, 114c, 115 Rectifying plate (Collisionplate) 116, 124, 134 Collision plate

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

An embodiment of the present invention will now be described withreference to the accompanying drawings. FIG. 1 is a side view showingthe overall configuration of an exhaust trap device 100 in accordancewith an embodiment of the present invention. The exhaust trap device 100includes a first trap unit 110, a second trap unit 120 and a third trapunit 130 arranged in series along an exhaust route of a gas. The firsttrap unit 110, the second trap unit 120 and the third trap unit 130 arecombined together as a single unit by means of a frame 101. Accordingly,each of the trap units can be separated by releasing them from the frame101. The first trap unit 110 has a gas inlet port connected to adownstream side of a valve 102 which may be a butterfly valve. The firsttrap unit 110 has a gas outlet port connected to a gas inlet port of thesecond trap unit 120 through a “U”-shaped exhaust line 103. The secondtrap unit 120 has a gas outlet port connected to a gas inlet port of thethird trap unit 130 through a joint flange 104. A valve 105 is providedat the downstream side of the third trap unit 130. The valve 105 can bea butterfly valve.

FIG. 2 is a vertical cross sectional view depicting an internalstructure of the first trap unit 110. FIG. 3 is a partial crosssectional view illustrating the internal structure of the first trapunit 110. FIG. 4 is a horizontal cross sectional view showing the firsttrap unit 110. FIG. 2 depicts a cross section taken along the line A-Bin FIG. 4, while FIG. 3 illustrates a cross section of an outer tubetaken along the line A′-B in FIG. 4 and a side profile of an inner tube.

The first trap unit 110 is of a dual tube structure having an outer tube113 and an inner tube 114. The outer tube 113 is connected to end plates111 and 112 at its opposite end portions, thus forming a cylindricalcase whose opposite ends are closed. A gas inlet port 110A is formed atthe portion of the outer tube 113 closer to the end plate 111. Anexhaust path 11X having a ring-like cross section is formed between theouter tube 113 and the inner tube 114. Ring-shaped collision plates orfins (not shown) may be provided at a portion of the innercircumferential surface of the outer tube 113, which faces the innertube 114 and is closer to the end plate 112 than the gas inlet port110A. The outer tube 113 has an extension section extending in an axialdirection beyond the end portion of the inner tube 114 at the side ofthe end plate 112. The internal space defined by the extension sectionacts as a path inverting portion 11Y which is connected with thedownstream side of the exhaust path 11X. The path inverting portion 11Yhas a function of receiving reaction by-products trapped in and peeledoff from the exhaust path 11X at the upstream side thereof. Asillustrated, a coolant path 113 s may be formed within a wall of theouter tube 113 around the path inverting portion 11Y in such a mannerthat a coolant such as water or the like can flow through the coolantpath 113 s. A ring-shaped collision plates or fins (not shown) can beprovided in the path inverting portion 11Y.

The inner tube 114 is not supported by the end plate 112 but by the endplate 111. At the side of the end plate 111, the inner tube 114 has anopening that communicates with a gas outlet port 110B through a holeformed through the end plate 111. At the side of the end plate 112, theinner tube 114 has an opening facing to the end plate 112 via the pathinverting portion 11Y. A coolant path 114 s is formed within a wall ofthe inner tube 114. Arranged on an external surface of the inner tube114 are rectifying plates 114 a, 114 b, 114 c and 114 d each extendingin the flow direction of an exhaust gas (in a downward direction inFIGS. 2 and 3) within the exhaust path 11X, namely in an axial directionof the inner tube 114 (which coincides with an axial direction of theexhaust path 11X). It is to be noted that, although the rectifyingplates 114 a, 114 b, 114 c and 114 d are most preferably extended in theaxial direction of the inner tube 114 (i.e., the angle being zerobetween the axis of the exhaust path 11X and the rectifying plates 114a, 114 b, 114 c, 114 d), it will be appropriate that the planes on whichthe rectifying plates lie are not perpendicular to the axis of the innertube 114. Therefore, the planes on which the rectifying plates lie maymake a predetermined angle with respect to the axis of the inner tube114, for example. In case that the rectifying plates are slanted to theaxis of the inner tube 114 in this manner, it is advantageous to makethe predetermined angle as small as possible and, more concretely, thepredetermined angle is preferably no greater than 45 degrees.Furthermore, the planes on which the rectifying plates lie may be curvedones. For the purpose of describing the embodiment in the subjectspecification, two different terms, “rectifying plates” and “collisionplates” are used to define plate-like bodies affecting the exhaust gasflow within the exhaust path. It should be appreciated, however, thatthe two terms are distinguished from each other only by the angle of theplate-like bodies with respect to the axis of the exhaust path in whichthe plate-like bodies are arranged. Thus, no clear demarcation lineexists between the two terms and, in this context, the “rectifyingplates” may be regarded as the “collision plates” that make a zero angleor a small angle with respect to the axis of the exhaust path.

As shown in FIG. 3, among these rectifying plates, the rectifying plate114 a located closest to the gas inlet port 110A is extended at theportion of the inner tube 114 that does not face the gas inlet port110A. The rectifying plate 114 b positioned farther from the gas inletport 110A than the rectifying plate 114 a extends closer to the endplate 111 than the rectifying plate 114 a. The rectifying plate 114 clying farther from the gas inlet port 110A than the rectifying plate 114b extends closer to the end plate 111 than the rectifying plate 114 b.The rectifying plate 114 d arranged farthest from the gas inlet port110A, i.e., disposed at a diametrically opposite side of the gas inletport 110A, extends closer to the end plate 111 than the rectifying plate114 c. By not providing rectifying plates within a predetermined extentaround the gas inlet port 110A in this way, the rectifying plates causeno hindrance to the flow of the exhaust gas introduced from the gasinlet port 110A.

As depicted in FIG. 4, the closer to the gas inlet port 110A therectifying plates are located, the smaller the rectifying platesprotrude into the exhaust path 11X. In other words, the rectifying plate114 a protrudes in a smaller amount than the rectifying plate 114 b. Therectifying plate 114 b protrudes into at a shorter distance than therectifying plate 114 c. The rectifying plate 114 c protrudes in asmaller amount than the rectifying plate 114 d. Due to this feature, theexhaust gas introduced from the gas inlet port 110A are readily spreadover the entire cross section of the exhaust path 11X, therebypreventing the solidified substances from being intensively accumulatedon and thus clogging a specific area of the exhaust path 11X (e.g., anarea in the vicinity of the gas introduction port 110A).

Furthermore, the rectifying plates 114 a, 114 b and 114 c are providedwith slits 114 ax, 114 bx and 114 cx formed between themselves and theouter circumference of the inner tube 114. These slits are provided inplural numbers with intervals therebetween along the length direction ofeach of the rectifying plates. Although the rectifying plate 114 d hasno slit in the illustrated embodiment, slits may also be provided on therectifying plate 114 d. Provision of the slits 114 ax, 114 bx and 114 cxallows parts of the exhaust gas to pass through the rectifying plates114 a, 114 b, 114 c and 114 d. This enables the exhaust gas to uniformlyflow through the exhaust path 11X, making it possible to efficientlytrap the reaction by-products. Provision of the slits 114 ax, 114 bx and114 cx allows parts of the exhaust gas to pass through the rectifyingplates 114 a, 114 b and 114 c. This enables the exhaust gas to uniformlyflow through the exhaust path 11X, making it possible to efficientlytrap the reaction by-products.

Moreover, although each of the rectifying plates 114 a, 114 b, 114 c and114 d of the illustrated embodiment is formed continuously along asingle generatrix on the outer circumference of the inner tube 114, butis not limited thereto. Alternatively, a plurality of short rectifyingplates may be arranged spaced apart along a single generatrix (namely,in the axial direction of the inner tube 114). As a further alternative,a plurality of short rectifying plates may be arranged on the outercircumference of the inner tube 114 in a lattice shape. However, it ispreferred that each of the short rectifying plates extends in the axialdirection of the inner tube 114.

An exhaust path 11Z is defined inside the inner tube 114. The exhaustpath 11Z extends long in a rectilinear manner, from a position where itis opened toward the path inverting portion 11Y at the side of the endplate 112 to a position where it adjoins the gas outlet port 110B. Inthe exhaust path 11Z, a plurality of collision plates 116 are arrangedin such a manner as to make a predetermined angle (a right angle in theillustrated example) with respect to the axial direction of the exhaustpath 11Z (the up-down direction in FIGS. 2 and 3). As illustrated inFIGS. 2 and 4, each of the collision plates 116 is shaped to block onlya part of the cross section of the exhaust path 11Z. When viewed in theaxial direction of the exhaust path 11Z, at least a part of the areablocked by one of the collision plates 116 is out of alignment with thearea blocked by another collision plate 116 neighboring the onecollision plate in the axial direction of the exhaust path 11Z. In theillustrated embodiment, the plurality of collision plates 116 arearranged in a spiral shape about the axis of the exhaust path 11Z atdifferent angular positions, whereby a vortex flow of the exhaust gas iscreated within the exhaust path 11Z. In the example shown in thedrawings, the angular positions of two neighboring collision plates 116are deviated from each other by 90 degrees. The plurality of thecollision plates 116 are formed of identically shaped plate-like bodiesand are attached to the inner circumference of the inner tube 114. Mostpreferably, each of the collision plates 116 is arranged on a planeperpendicularly intersecting the axis of the exhaust path 11Z. However,it will be appropriate if the angles that the planes on which thecollision plates 116 are arranged make with respect to the axis of theexhaust path 11Z are greater than those that the planes on which therectifying plates 114 a, 114 b, 114 c and 114 d are arranged make withrespect to the axis of the exhaust path 11X; and the angles arepreferably greater than 45 degrees. Furthermore, the planes on which thecollision plates 116 lie may be curved ones.

The plurality of collision plates 116 are arranged within the exhaustpath 11Z in such a manner that there exists in the exhaust path 11Z aspace extending continuously in the axial direction of the exhaust path11Z without being interrupted by any of the collision plates 116arranged within the exhaust path 11Z. This space can be recognized asthe area of a rectangular or square cross section designated by thereference character 11Zt in FIG. 4. In the illustrated embodiment, thespace 11Zt extends rectilinearly so that at least a part of the exhaustgas introduced into the exhaust path 11Z can directly pass through theexhaust path 11Z without being blocked by the collision plates 116. Thespace 11Zt extends through the center region of the exhaust path 11Z.Provision of the space 11Zt suppresses the trapping action fromintensively occurring within the exhaust path 11Z and thus allows thetrapping action to be also carried out at the downstream side of theexhaust path 11Z of the exhaust trap device 100.

In the present embodiment, the exhaust path 11X defined between theouter tube 113 and the inner tube 114 communicates with the exhaust path11Z defined inside the inner tube 114 through the path inverting portion11Y. In particular, the path inverting portion 11Y allows the exhaustpath 11X and the exhaust path 11Z to communicate with each other overtheir entire perimeters. The path inverting portion 11Y is formed of aspace defined inside the extended section of the outer tube 113 whichextends longer in the axial direction than the end portion of the innertube 114. Rectifying plates may be provided on the inner circumferenceof the outer tube 113 adjoining the path inverting portion 11Y.

As shown in FIG. 2, the coolant path 114 s formed within the wall of theinner tube 114 communicates with a flow path inlet 111 a provided insidethe end plate 111 via a pipe 114 t. The pipe 114 t extends from the flowpath inlet 111 a into the coolant path 114 s. The coolant path 114 s isalso in communication with a flow path outlet 111 b formed inside theend plate 111. The flow path inlet 111 a is connected to a coolant inletport 110 x shown in FIG. 1, while the flow path outlet 111 b isconnected to a coolant outlet port 110 y illustrated in FIG. 1.Furthermore, the coolant path 113 s of the outer tube 113 arrangedoutside the path inverting portion 11Y is connected to a coolant inletport 110 z and a coolant outlet port 110 u as depicted in FIG. 1. Thisstructure ensures that a coolant is introduced into the bottom of thecoolant path 114 s via the pipe 114 t and then flows toward the top ofthe coolant path 114 s. Thus, it is possible to suppress occurrence ofconvection of the coolant within the coolant path 114 s, which helps toefficiently perform a cooling operation.

As set forth above, the first trap unit 110 includes one exhaust trapsection having the exhaust path 11X defined between the outer tube 113and the inner tube 114 and the other exhaust trap section having theexhaust path 11Z defined inside the inner tube 114. In other words, theexhaust path 11X is arranged to surround the exhaust path 11Z. Therectifying plates 114 a, 114 b, 114 c and 114 d are arranged in theexhaust path 11X so as to extend along the flow direction of the exhaustgas. Further, the exhaust path 11Z is connected to the downstream sideof the exhaust path 11X through the path inverting portion 11Y. Thecollision plates 116 for baffling the flow of the exhaust gas arearranged in the exhaust path 11Z. The flow direction of the exhaust gasin the exhaust path 11X is opposite to that in the exhaust path 11Z.

Next, the structure of the second trap unit 120 will be described withreference to FIGS. 5A and 5B. The second trap unit 120 includes an endplate 121 having an opening adjacent to a gas inlet port 120A, an endplate 122 having an opening adjacent to a gas outlet port 120B, and anouter wall 123 connected at its opposite ends to the end plates 121 and122. A coolant path 123 s is formed within the outer wall 123. Thecoolant path 123 s is connected to a coolant inlet port 120 x and acoolant outlet port 120 y illustrated in FIG. 1.

An exhaust path 12X is defined inside the second trap unit 120 betweenthe gas inlet port 120 a and the gas outlet port 120B. The exhaust path12X is formed in a rectilinear shape. Alternatively, the exhaust path12X may be of a spiral shape or a curved shape. Arranged within theexhaust path 12X are collision plates 124 that serve to block only partsof the cross section of the exhaust path 12X. As illustrated in FIG. 5B,each of the collision plates 124 is shaped to block only a part of thecross section of the exhaust path 12X. When viewed in the axialdirection of the exhaust path 12X, at least a part of the area blockedby one of the collision plates 124 is out of alignment with the areablocked by another collision plate 124 neighboring the one collisionplate in the axial direction of the exhaust path 12X. In the illustratedembodiment, the plurality of collision plates 124 are arranged in aspiral shape about the axis of the exhaust path 12X at different angularpositions. In the example shown in the drawings, the angular positionsof two neighboring collision plates 124 are deviated from each other by120 degrees. The plurality of the collision plates 124 are formed ofidentically shaped plate-like bodies and are attached to the innercircumference of the outer wall 123. Most preferably, each of thecollision plates 124 is arranged on a plane perpendicularly intersectingthe axis of the exhaust path 12X. However, it will be appropriate if theangles that the planes on which the collision plates 124 are arrangedmake with respect to the axis of the exhaust path 12X are greater thanthose that the planes on which the rectifying plates 114 a, 114 b, 114 cand 114 d are arranged make with respect to the axis of the exhaust path11X; and the angles are preferably greater than 45 degrees. Furthermore,the planes on which the collision plates 124 lie may be curved ones.

The plurality of collision plates 124 are arranged within the exhaustpath 12X in such a manner that there exists in the exhaust path 12X aspace extending continuously in the axial direction of the exhaust path12X without being interrupted by any of the collision plates 124arranged within the exhaust path 12X. This space can be recognized asthe area of a triangular, particularly, equilateral triangular crosssection designated by the reference character 12Xt in FIG. 5B. In theillustrated embodiment, the space 12Xt extends rectilinearly so that atleast a part of the exhaust gas introduced into the exhaust path 12X candirectly pass through the exhaust path 12X without being blocked by thecollision plates 124. The space 12Xt extends through the center regionof the exhaust path 12X. Provision of the space 12Xt suppresses thetrapping action from intensively occurring within the exhaust path 12Xand thus allows the trapping action to be also carried out at thedownstream side of the exhaust path 12X of the exhaust trap device 100.

Next, the structure of the third trap unit 130 will be described withreference to FIGS. 6A and 6B. The third trap unit 130 includes an endplate 131 having an opening adjacent to a gas inlet port 130A, an endplate 132 having an opening adjacent to a gas outlet port 130B, and anouter wall 133 connected at its opposite ends to the end plates 131 and132. A coolant path 133 s is formed within the outer wall 133. Thecoolant path 133 s is connected to a coolant inlet port 130 x and acoolant outlet port 130 y as illustrated in FIG. 1.

An exhaust path 13X is defined inside the third trap unit 130 betweenthe gas inlet port 130A and the gas outlet port 130B. The exhaust path13X is formed in a rectilinear shape. Alternatively, the exhaust path13X may be of a spiral shape or a curved shape. Arranged within theexhaust path 13X are collision plates 134 that serve to block only partsof the cross section of the exhaust path 13X. As illustrated in FIG. 6B,each of the collision plates 134 is shaped to block only a part of thecross section of the exhaust path 13X. When viewed in the axialdirection of the exhaust path 13X, at least a part of the area blockedby one of the collision plates 134 is out of alignment with the areablocked by another collision plate 134 neighboring the one collisionplate in the axial direction of the exhaust path 13X. In the illustratedembodiment, the plurality of collision plates 134 are arranged in aspiral shape about the axis of the exhaust path 13X at different angularpositions. In the example shown in the drawings, the angular positionsof two neighboring collision plates 134 are deviated from each other by120 degrees. The plurality of collision plates 134 are formed ofidentically shaped plate-like bodies and are attached to the innercircumference of the outer wall 133. Most preferably, each of thecollision plates 134 is arranged on a plane perpendicularly intersectingthe axis of the exhaust path 13X. However, it will be good if the anglesthat the planes of the collision plates 134 make with respect to theaxis of the exhaust path 13X are greater than those that the planes ofthe rectifying plates 114 a, 114 b, 114 c and 114 d make with respect tothe axis of the exhaust path 11X; and the angles are preferably greaterthan 45 degrees. Furthermore, the planes on which the collision plates134 lie may be curved ones.

In the exhaust path 13X, there exists no such space as the spaces 11Ztand 12Xt employed in the first trap unit 110 and the second trap unit120 and adapted to extend continuously through the exhaust paths in theaxial directions thereof without being interrupted by any of thecollision plates. In other words, in the exhaust path 13X all of thelines extending in the axial direction of the exhaust path 13X intersectthe collision plates 134. Thus, even a part of the exhaust gasintroduced into the exhaust path 13X is not allowed to pass through theexhaust path 13X without being interrupted by the collision plates 134,which means that the entire exhaust gas is deflected by the collisionplates 134 while moving forward through the exhaust path 13X.

In the exhaust trap device 100 noted above, the first trap unit 110, thesecond trap unit 120 and the third trap unit 130 are arranged in thenamed sequence along the exhaust route. More specifically, the exhausttrap section provided in the exhaust path 11X of the first trap unit110, the exhaust trap section provided in the exhaust path 11Z of thefirst trap unit 110, the exhaust trap section provided in the exhaustpath 12X of the second trap unit 120 and the exhaust trap sectionprovided in the exhaust path 13X of the third trap unit 130 are arrangedone after another along the exhaust route.

In the present embodiment, the interior of the respective trap units iscooled by circulating the coolant such as water or the like through thetrap units, and solid matter (e.g., reaction by-products) is solidifiedand trapped by cooling the hot exhaust gas. To be more specific, thecoolant is supplied to the coolant path 133 s from the coolant inletport 130 x of the third trap unit 130 arranged at the downstreammostside of the exhaust trap device and then is discharged through thecoolant outlet port 130 y. The coolant thus discharged is supplied tothe coolant path 123 s from the coolant inlet port 120 x of the secondtrap unit 120 arranged at the upstream side of the third trap unit 130and then is discharged through the coolant outlet port 120 y. Thecoolant thus discharged is supplied to the coolant path 114 s from thecoolant inlet port 110 x of the first trap unit 110 arranged at theupstreammost side of the exhaust trap device and then is dischargedthrough the coolant outlet port 110 y. The coolant thus discharged issupplied to the coolant path 113 s of the first trap unit 110 from thecoolant inlet port 110 z and then is discharged through the coolantoutlet port 110 u.

In this way, the coolant paths 113 s, 114 s, 123 s and 133 s provided inthe respective trap units 110, 120 and 130 of the exhaust trap device100 are connected in series, and the coolant is sequentially circulatedfrom a coolant path arranged at a more downstream side in the flowdirection of the exhaust gas toward a coolant path arranged at a moreupstream side. Therefore, a cooling temperature by the coolant patharranged at the more upstream side in the flow direction of the exhaustgas is relatively high and the cooling temperature by the coolant patharranged at the more downstream side is relatively low. Accordingly, theexhaust gas is gradually cooled down to a lower temperature as it movestoward the downstream side along the exhaust route. This makes itpossible to distribute the amount of accumulation of the solidifiedsubstances over the plurality of exhaust trap sections and thus torelieve uneven distribution in the amount of accumulation of thesolidified substances, eventually reducing the frequency of maintenancefor the exhaust trap device 100. In the embodiment set forth above, thesolidification reaction is promoted by cooling the unreacted gasintroduced into the exhaust trap device 100. However, depending on thekind of a gas used, the solidification reaction may be promoted byheating the unreacted gas. In such a case, it will be preferable tocirculate a heated medium through the coolant paths 113 s, 114 s, 123 sand 133 s of the respective trap units 110, 120 and 130. In this case,it is also possible to relieve uneven distribution in the amount ofaccumulation of the solidified substances by allowing the heated mediumto sequentially circulate from the coolant path (medium path) arrangedat the more downstream side in the flow direction of the exhaust gastoward the coolant path (medium path) arranged at the more upstreamside.

Furthermore, in the present embodiment, the space 11Zt extendscontinuously through the exhaust path 11Z, which constitutes one of theinner and outer exhaust trap sections of the first trap unit 110, in theaxial direction of the exhaust path 11Z without being interrupted by anyof the collision plates 116. Furthermore, the space 12Xt extendscontinuously through the exhaust path 12X, which constitutes the exhausttrap section of the second trap unit 120 arranged at the downstream sideof the first trap unit 110, in the axial direction of the exhaust path12X without being interrupted by any of the collision plates 124. Inaddition, the collision plates 134 are arranged in the exhaust trapsection of the third trap unit 130 at the downstreammost side in such amanner as to leave no space like the spaces 11Zt and 12Xt.

Accordingly, in the exhaust paths 11Z and 12X of the two upstream sideexhaust trap sections, a part of the exhaust gas moves through thespaces 11Zt and 12Xt without being interrupted by any of the collisionplates 116 and 124, which leads to reduction in the amount ofaccumulation of the solid matter solidified from the exhaust gas. On theother hand, in the exhaust path 13X of the exhaust trap section disposedat the downstreammost side, the exhaust gas is sufficiently contactedwith the collision plates 134 and therefore the solid matter solidifiedin that exhaust path is trapped in a reliable manner. This makes itpossible to suppress reduction in the conductance or clogging of theexhaust path which would otherwise occur at the upstream side by theintensive accumulation of the solid matter. As a result, it becomespossible to reduce the frequency of maintenance and also to reliablytrap the solidified substances in the downstream exhaust trap section,thus avoiding outflow of the solidified components toward the downstreamside of the exhaust trap device 100.

In the present embodiment, the rectifying plates 114 a, 114 b, 114 c and114 d are arranged in the exhaust path 11X, which constitutes theupstream exhaust trap section of the two exhaust trap sections of thefirst trap unit 110, in such a manner as not to hinder the exhaust gasflow. The rectifying plates serve to increase the internal surface areaof the exhaust path 11X on which the solid matter solidified from theexhaust gas can be accumulated in a dispersed manner. Thanks to the factthat the rectifying plates are disposed so as not to hinder the exhaustgas flow, it is possible to prevent the solid matter from beingintensively accumulated at a part of the exhaust path 11X, which helpsto suppress reduction at a part of the exhaust conductance or cloggingof the exhaust route. In contrast, the collision plates 116 are arrangedwithin the exhaust path 11Z constituting the downstream exhaust trapsection of the first trap unit 110, in such a manner as to hinder anddeflect the exhaust gas flow. This reliably improves the efficiency oftrapping the solid matter in the exhaust path 11Z.

Accordingly, the first trap unit 110 alone can reduce unevendistribution in the amount of accumulation of the solidified substancesand consequently curtail the frequency of maintenance. It is alsopossible to diminish outflow of the solidified components toward thedownstream side of the exhaust trap device 100.

Particularly, the first trap unit 110 includes the path invertingportion 11Y lying between the upstream exhaust path 11X and thedownstream exhaust path 11Z. In order to avoid clogging of the pathinverting portion 11Y, the path inverting portion 11Y is designed tohave a cross sectional communication area greater than those of theupstream exhaust path 11X and the downstream exhaust path 11Z. Thereason for this is that the flow direction of the exhaust gas isinverted in the path inverting portion 11Y and hence most of the exhaustgas collides against the inner surface of the path inverting portion11Y, thereby increasing the amount of the solid matter trapped in thepath inverting portion 11Y. However, fins for trapping the solid mattermay be provided in the path inverting portion 11Y.

In the first trap unit 110 of the present embodiment, the exhaust paths11X and 11Z communicating with each other through the path invertingportion 11Y are overlapped one inside the other, and the flow directionsof the exhaust gas in the exhaust paths 11X and 11Z are opposite. Thishelps to make compact the whole device configuration, while securing thecross sectional communication areas of the respective exhaust paths.

In the present embodiment, the exhaust trap section having the exhaustpath 11X, the exhaust trap section having the exhaust path 11Z, theexhaust trap section having the exhaust path 12X and the exhaust trapsection having the exhaust path 13X are arranged in series. However,exhaust trap sections may be serially arranged in a manner other thanthe described. For example, in the configuration noted above, one of thesecond trap unit (the exhaust trap section with the exhaust path 12X)and the third trap unit (the exhaust trap section with the exhaust path13X) may have the same structure as the other. Furthermore, the exhausttrap device 100 may be formed of only the first and the second trapunits or the first and the third trap units. Moreover, the exhaust trapdevice 100 may be formed of the exhaust trap section having the exhaustpath 13X and one of the exhaust trap section having the exhaust path 11Zand the exhaust trap section having the exhaust path 12X only. Inaddition, the exhaust trap device 100 may be formed of only the exhausttrap section having the exhaust path 11X and one of the exhaust trapsection having the exhaust path 11Z, the exhaust trap section having theexhaust path 12X and the exhaust trap section having the exhaust path13X.

Next, description will be given to the configuration of a gas reactionapparatus incorporating the exhaust trap device 100 described above.FIG. 7 is a schematic diagram illustrating one exemplary configurationof a gas reaction apparatus in accordance with the present embodiment.The gas reaction apparatus includes a gas supply unit 1, a gas reactionchamber 2, exhaust trap devices 100 and 3, and an evacuation device 4.The gas supply unit 1 is provided with source vessels 1A, 1B and 1C forreceiving source materials and a solvent vessel 1D for receiving asolvent such as an organic solvent or the like. For instance, if metalorganic compounds (organic metals) of, e.g., Pb, Zr, Ti or the like, areliquids, the source vessel 1A, 1B and 1C accommodate therein the metalorganic compounds themselves or diluted ones with a solvent such as anorganic solvent or the like, or if they are solids, they are dissolvedby a solvent such as an organic solvent or the like and are accommodatedin the source vessels 1A, 1B and 1C.

Pressure lines 1 ax, 1 bx, 1 cx and 1 dx for supplying inert gases suchas N₂, He, Ar or the like or other pressurized gases lead into thesource vessels 1A to 1C and the solvent vessel 1D. Whereas outlet pipes1 ay, 1 by, 1 cy and 1 dy for drawing the liquid source materials or thesolvent extend from the source vessels 1A to 1C and the solvent vessel1D. The outlet pipes 1 ay to 1 dy are connected to a joint line 1 p viamass flow controllers 1 az, 1 bz, 1 cz and 1 dz, respectively. The jointline 1 p is connected to a vaporizer 1E.

If the pressurized gases are supplied through the pressure lines 1 ax to1 dx, the liquid source materials or the solvent are extruded into theoutlet pipes 1 ay to 1 dy and then sent to the joint line 1 p with theflow rates thereof controlled by the mass flow controllers 1 az to 1 dz.An inlet gas such as N₂, He, Ar or the like or other carrier gas issupplied to the joint line 1 p. The carrier gas and the liquid sourcematerials or the solvent are mixed into a gas-liquid mixture and thensupplied to the vaporizer 1E. The vaporizer 1E has a heated vaporizingchamber into which the liquid source materials are sprayed and vaporizedto produce source gases. The source gases are sent to the gas reactionchamber 2 via a source gas supply line 1 q.

The gas supply unit 1 farther includes a reaction gas supply line 1 rconnected to the gas reaction chamber 2 in parallel with the source gassupply line 1 q and a carrier gas supply line 1 s merged with the sourcegas supply line 1 q immediately ahead of the gas reaction chamber 2.Supplied through the reaction gas supply line 1 r is a reaction gas (O₂,NH₄, Cl₂ and so forth) that serves to make a prescribed reaction withthe source gas introduced from the source gas supply line 1 q.

The gas reaction chamber 2 is an air-tight chamber provided with anenergy applying unit such as a heating unit, e.g., a heater or the like,or an electric discharge unit, e.g., a discharging part or the like.Arranged within the air-tight chamber are a gas inlet unit 2 a (e.g., apart having a multiplicity of gas inlet holes just like a shower head),and a susceptor 2 b kept in a confronting relationship with the gasinlet unit 2 a. A substrate W formed of a semiconductor substrate or thelike is mounted on the susceptor 2 b. In the present embodiment, thesource gas and the reaction gas introduced from the gas inlet unit 2 aare properly reacted with each other in the air-tight chamber byattaining the energy applied by the energy applying unit, forming agiven thin film on the surface of the substrate W. Here, if a PZT thinfilm is to be formed on the substrate W for instance, the substratetemperature is usually about 500-700° C. and the temperature of theexhaust gas discharged from the gas reaction chamber 2 is approximately200° C.

An exhaust line 2 p is connected to the air-tight chamber and leads tothe exhaust trap device 100 set forth earlier. The exhaust trap device100 is connected to an exhaust line 100 p, which is connected to anevacuation device 4 formed of a vacuum pump or the like. The source gassupply line 1 q is connected to a bypass line 2 q just ahead of the gasreaction chamber 2, which leads to an exhaust trap device 3. The exhausttrap device 3 is connected to the exhaust line 100 p via a bypass line 3q.

The gas reaction chamber 2 is decompressed through the exhaust line 2 p,the exhaust trap device 100 and the exhaust line loop by virtue of theevacuation device 4 and is kept at a predetermined pressure. As theafore-mentioned reaction occurs within the gas reaction chamber 2, theexhaust gas is discharged toward the evacuation device 4 through theexhaust trap device 100 where the reaction by-products are trapped.Here, the source gas supplied through the source gas supply line 1 qfrom the gas supply unit 1 is bypassed to the evacuation device 4 viathe bypass line 2 q, the exhaust trap device 3 and the bypass line 3 q,until the composition of the source gas is stabilized and the gasreaction chamber 2 becomes ready for operation or after the reaction inthe gas reaction chamber 2 has been completed. The gas bypassed at thistime is the source gas itself that does not pass through the gasreaction chamber 2. Solidified substances are also trapped by theexhaust trap device 3 from the source gas.

Although FIG. 7 shows an example wherein the exhaust trap device 100 ofthe present invention is connected to the exhaust route of the gasreaction chamber 2, the exhaust trap device 100 may be employed as theexhaust trap device alternatively arranged in the middle of the exhaustroute (bypass line) connected to the gas supply unit 1 to trap thesource gas, just like the exhaust trap device 3.

It should be understood that the exhaust trap device and the gasreaction apparatus of the present invention are not restricted to theembodiment shown and described above but may be modified in manydifferent ways without departing from the scope of the invention. Takingan example, the axes of the exhaust paths constituting the respectiveexhaust trap sections may be of a curved shape or an angled shape,although they are formed in a rectilinear shape in the exhaust trapdevice 100 of the aforementioned embodiment.

In place of the plurality of collision plates arranged in the exhaustpaths, an integrally formed spiral collision plate (screw-like collisionplate) whose axis coincides with the axis of each of the exhaust pathsmay be provided. In this case, a gap may be left between the inner orouter circumference of the spiral collision plate and the wall of thecorresponding exhaust path, thereby providing the same space as theabove-noted spaces 11Zt and 12Xt in the exhaust path.

Although the spaces 11Zt and 12Xt are all provided at the centersportions of the exhaust paths, they may be formed along the outerportions circumferences of the exhaust paths or may be created byforming through-holes on the collision plates.

A film forming apparatus for forming a thin film on a substrate has beendescribed as an example of the gas reaction apparatus. The film formingsystem may be exemplified by cases forming a TiN film by the reaction ofTiCl₄ and NH₃ to produce NH₄CL as a reaction by-product; a SiN film bythe reaction of SiH₄ or SiH₂Cl₂ and NH₃ to produce NH₄Cl as a reactionby-product; a WN film by the reaction of WF₆ and NH₃ to produce NH₄F asa reaction by-product; a TaN film by the reaction of TaCl₄ and NH₃ toproduce NH₄Cl as a reaction by-product; and other metal oxide films.Objects trapped are not restricted to the reaction by-products describedabove but may include an excess reaction gas remaining unreacted. Thepresent invention may be equally applied to other gas reactionapparatuses than the film forming apparatus for semiconductor devices,e.g., a dry etching apparatus or an apparatus for the production of LCD.

1. An exhaust trap device for trapping solidified substances from anexhaust gas passing through a gas exhaust route, comprising: a pluralityof exhaust trap sections arranged in series along the exhaust route,each section having an internally formed exhaust path through which theexhaust gas passes, wherein the plurality of exhaust trap sectionsincludes a first exhaust trap section arranged at an upstream side in aflow direction of the exhaust gas and a second exhaust trap sectionarranged at a downstream side in the flow direction of the exhaust gas,wherein the first exhaust trap section is provided with one or morecollision plates arranged to interrupt an exhaust gas flow moving alongan axis of an exhaust path of the first exhaust trap section, thecollision plates being arranged such that a space extending continuouslyalong the axis of the exhaust path without being interrupted by any ofthe collision plates arranged within the exhaust path exists in theexhaust path, and wherein the second exhaust trap section is providedwith a plural number of collision plates arranged to interrupt anexhaust gas flow moving along an axis of an exhaust path of the secondexhaust trap section, the plural number of collision plates beingarranged such that a space extending continuously along the axis of theexhaust path without being interrupted by any of the collision platesarranged within the exhaust path does not exist in the exhaust path. 2.The exhaust trap device of claim 1, wherein the plurality of exhausttrap sections are constructed to be connected to and separated from eachother.
 3. The exhaust trap device of claim 1, wherein the collisionplates are arranged to allow the exhaust gas to spirally flow within theexhaust path in which the collision plates are arranged.
 4. A gasreaction apparatus comprising: a gas supply unit; a gas reaction chamberin which gases supplied from the gas supply unit are reacted; an exhaustroute associated with the gas supply unit or the gas reaction chamber;and the exhaust trap device as recited in claim 1, the exhaust trapdevice being arranged on the exhaust route.